redis / TODO

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Redis TODO

WARNING: are you a possible Redis contributor?
         Before implementing what is listed in this file
         please drop a message in the Redis google group or chat with
         antirez or pietern on #redis to check if the work
         is already in progress and if the feature is still interesting for
         us, and *how* exactly this can be implemented to have good changes
         of a merge. Otherwise it is probably wasted work! Thank you


* Implement rehashing and cluster check in redis-trib.
* Reimplement MIGRATE / RESTORE to use just in memory buffers (no disk at
  all). This will require touching a lot of the RDB stuff around, but we may
  hand with faster persistence for RDB.
* Implement the slave nodes semantics and election.
* Allow redis-trib to create a cluster-wide snapshot (using SYNC).
* Allow redis-trib to restore a cluster-wide snapshot (implement UPLOAD?).


* SCRIPT FLUSH or alike to start a fresh interpreter?


* SORT: Don't copy the list into a vector when BY argument is constant.
* Write the hash table size of every db in the dump, so that Redis can resize the hash table just one time when loading a big DB.
* Read-only mode for slaves.
* Redis big lists as linked lists of small ziplists?
  Possibly a simple heuristic that join near nodes when some node gets smaller than the low_level, and split it into two if gets bigger than high_level.


* #519: Slave may have expired keys that were never read in the master (so a DEL
  is not sent in the replication channel) but are already expired since
  a lot of time. Maybe after a given delay that is undoubtably greater than
  the replication link latency we should expire this key on the slave on